Squirrel cage question

Is it a special fan that is used to inflate the air in between the two layers in hoophouses? I understand the basic concept of pulling air from outside the GH and blowing it in between the two layers.

Thanks!

MollyD

Yes Molly-thats exactly what it is. It is small-about .5hp. To be effective, the space between the two layers of plastic should be anywhere between .5" and 4" when the motor is blowing the air between them. Works nicely, I would say that you get an extra up to 10 degrees of warmth from doing it.

Thanks Tigerlily!

One more question if you don't mind. The fan pulls air from outside into the space in between the layers but where does the air already in the layers go to?? Does it reach a 'full' point where the fan stops running?
I didn't use one before and wondered if my cattlepanel hoophouse would benefit from one.

MollyD

The fan (aside from the initial filling of the space) pumps almost no air once the plastic has inflated. The power consumption also drops very low so you don't need a large fan at all. A 1/16 to 1/8 hp fan should be enough. In a new installation with tight sealing of the plastic there is almost no air flow, but the fan needs to stay on to maintain enough static pressure to keep the plastic layers apart.

Unfortunately cats and other varmints like to climb on the plastic especially when covered by shading and they can put hundreds of small holes that will eventually cause leaks and decreased effective insulation.

You know, Molly, thats a good question, but I think that the air must slowly seep out where the plastic is stapled/attached at the base if you were to turn the motor off. I know that if I do turn the motor off, then the plastic will deflate at some point. So yes, you just keep the fan running the whole time, there is no "full" point.

If you have a plastic covering right now on your cattle hoophouse, then I don't see why you could not attach a second layer on top of the first. The key to the second layer is to put it on when you have a warm, sunny day so the plastic is not constricted, and to not pull it tight at all. Just staple it in place-the fan will push it away from the first layer. If I think of it, I will take pictures of what mine look like with the fan blowing air. I just replaced the plastic on all of them and they look so nice and clean-I should show them off!! lol

edited to add that the reason that I have .5hp is that I have larger grhouses and more space to fill.

This message was edited Dec 20, 2007 9:43 AM

Thanks Dave, no shade cloths here as we get very little sunshine all winter! So far (second year) no one has tried to climb the GH but we're way out in the country so very few neighborhood pets to bother things.

Thanks Tigerlily. I have the film on the outside and the inside is enclosed in clear solar pool cover. Could that serve as the second layer? It's too cold here now to add another layer of plastic.

MollyD